KYORITSU 6305 Instruction Manual - Manual (Page 5)

KEW6305
4
O Measurement Category
To ensure safe operation of measuring instruments, IEC 61010 establishes safety standards for
various electrical environments, categorized as O to CAT.IV, and called measurement categories.
Higher-numbered categories correspond to electrical environments with greater momentary
energy,
so a measuring instrument designed for CAT.III environments can endure greater momentary
energy
than one designed for CAT.II.
O : Circuits which are not directly connected to the mains power supply.
CAT.II : Electrical circuits of equipment connected to an AC electrical outlet by a power cord.
CAT.III : Primary electrical circuits of the equipment connected directly to the distribution panel,
and feeders from the distribution panel to outlets.
CAT.IV : The circuit from the service drop to the service entrance, and to the power meter and
primary overcurrent protection device (distribution panel).